Liquid, radiation-curable composition, especially for stereolithography

ABSTRACT

A liquid, radiation-curable composition which in addition to a liquid, free-radically polymerizable component comprises at least the following additional components: (A) from 40 to 80 percent by weight of a liquid difunctional or more highly functional epoxy resin or of a liquid mixture consisting of difunctional or more highly functional epoxy resins; (B) from 0.1 to 10 percent by weight of a cationic photoinitiator or of a mixture of cationic photoinitiators; and (C) from 0.1 to 10 percent by weight of a free-radical photoinitiator or of a mixture of free-radical photoinitiators; and (D) up to 40 percent by weight of a hydroxy compound, in which composition component (D) is selected from the group consisting of: 
     (D1) phenolic compounds having at least 2 hydroxyl groups, 
     (D2) phenolic compounds having at least 2 hydroxyl groups, which are reacted with ethylene oxide, proplyene oxide or with ethylene oxide and propylene oxide, 
     (D3) aliphatic hydroxy compounds having not more than 80 carbon atoms, 
     (D4) compounds having at least one hydroxyl group and at least one epoxide group, and 
     (D5) a mixture of at least 2 of the compounds mentioned under (D1) to (D4), and component (D) is present in the compositions in a quantity of at least 2 percent by weight; the free-radically polymerizable component comprises at least (E) from 4 to 30 percent by weight of at least one liquid poly(meth)acrylate having a (meth)acrylate functionality of more than 2; and at least one of components (A) and (D) comprises substances which have aromatic carbon rings in their molecule, is particularly suitable for stereolithography, a particular feature of this composition being that it leads to cured material which exhibits only a very low propensity for uptake of water.

The present invention relates to a liquid, radiation-curable compositionwhich is particularly suitable for the production of three-dimensionalshaped articles by means of stereolithography, to a process for theproduction of a cured product and, in particular, for thestereolithographic production of a three-dimensional shaped article fromthis composition.

The production of three-dimensional articles of complex shape by meansof stereolithography has been known for a relatively long time. In thistechnique the desired shaped article is built up from a liquid,radiation-curable composition with the aid of a recurring, alternatingsequence of two steps (a) and (b); in step (a), a layer of the liquid,radiation-curable composition, one boundary of which is the surface ofthe composition, is cured with the aid of appropriate radiation,generally radiation produced by a preferably computer-controlled lasersource, within a surface region which corresponds to the desiredcross-sectional area of the shaped article to be formed, at the heightof this layer, and in step (b) the cured layer is covered with a newlayer of the liquid, radiation-curable composition, and the sequence ofsteps (a) and (b) is repeated until a so-called green model of thedesired shape is finished. This green model is, in general, not yetfully cured and must therefore, normally, be subjected to post-curing.

The mechanical strength of the green model (modulus of elasticity,fracture strength), also referred to as green strength, constitutes animportant property of the green model and is determined essentially bythe nature of the stereolithographic-resin composition employed. Otherimportant properties of a stereolithographic-resin composition include ahigh sensitivity for the radiation employed in the course of curing anda minimum curl factor, permitting high shape definition of the greenmodel. In addition, for example, the precured material layers should bereadily wettable by the liquid stereolithographic-resin composition, andof course not only the green model but also the ultimately cured shapedarticle should have optimum mechanical properties.

Liquid, radiation-curable compositions for stereolithography which meetthe abovementioned requirements are described, for example, in EP-A-0605 361. These compositions are so-called hybrid systems, comprisingfree-radically and cationically photopolymerizable components. Inaddition to the liquid, free-radically polymerizable component, thesecompositions comprise at least:

(A) from 40 to 80 percent by weight of a liquid difunctional or morehighly functional epoxy resin or of a liquid mixture consisting ofdifunctional or more highly functional epoxy resins;

(B) from 0.1 to 10 percent by weight of a cationic photoinitiator or ofa mixture of cationic photoinitiators; and

(C) from 0.1 to 10 percent by weight of a free-radical photoinitiator orof a mixture of free-radical photoinitiators; and

(D) up to 40 percent by weight of a certain hydroxy compound.

This hydroxy component (D) is selected from the group consisting ofOH--terminated polyethers, polyesters and polyurethanes and is presentin the compositions in a quantity of at least 5 percent by weight; thefree-radically polymerizable component of said compositions additionallycomprises the following constituents:

(E) from 0 to 15 percent by weight of at least one liquidpoly(meth)acrylate having a (meth)acrylate functionality of more than 2,and

(F) from 5 to 40 percent by weight of at least one liquid cycloaliphaticor aromatic diacrylate, the content of component (E) being not more than50 percent by weight of the entire (meth)acrylate content.

These stereolithographic-resin compositions, however, lead to shapedarticles which still exhibit a relatively high water uptake, which isundesirable in many cases. One object of the present invention,therefore, is to improve these hybrid systems such that the water uptakeof a shaped article produced using them is decreased. At the same time,the other properties important for stereolithography, for example theproperties already mentioned above, should at least substantially beretained.

In accordance with the invention this object is achieved by theprovision of a liquid, radiation-curable composition comprising inaddition to a liquid, free-radically polymerizable component at leastthe following additional components:

(A) from 40 to 80 percent by weight of a liquid difunctional or morehighly functional epoxy resin or of a liquid mixture consisting ofdifunctional or more highly functional epoxy resins;

(B) from 0.1 to 10 percent by weight of a cationic photoinitiator or ofa mixture of cationic photoinitiators; and

(C) from 0.1 to 10 percent by weight of a free-radical photoinitiator orof a mixture of free-radical photoinitiators; and, in addition to theabovementioned components,

(D) up to 40 percent by weight of a hydroxy compound, in whichcomposition component (D) is selected from the group consisting of:

(D1) phenolic compounds having at least 2 hydroxyl groups,

(D2) phenolic compounds having at least 2 hydroxyl groups, which arereacted with ethylene oxide, proplyene oxide or with ethylene oxide andpropylene oxide,

(D3) aliphatic hydroxy compounds having not more than 80 carbon atoms,

(D4) compounds having at least one hydroxyl group and at least oneepoxide group, and

(D5) a mixture of at least 2 of the compounds mentioned under (D1) to(D4), and component (D) is present in the compositions in a quantity ofat least 2 percent by weight; the free-radically polymerizable componentcomprises at least

(E) from 4 to 30 percent by weight of at least one liquidpoly(meth)acrylate having a (meth)acrylate functionality of more than 2;and at least one of components (A) and (D) comprises substances whichhave aromatic carbon rings in their molecule.

As an optional additional component, the novel composition mayadditionally, in particular, comprise

(F) one or more di(meth)acrylates, preferably in a quantity of from 5 to40 percent by weight.

The epoxy resins which may be used in the novel compositions areexpediently resins which are liquid at room temperature and which onaverage possess more than one epoxide group (oxirane ring) in themolecule. Such resins may have an aliphatic, aromatic, cycloaliphatic,araliphatic or heterocyclic structure; they contain epoxide groups asside groups, or these groups form part of an alicyclic or heterocyclicring system. Epoxy resins of these types are known in general terms andare commercially available.

Polyglycidyl esters and poly(β-methylglycidyl) esters are one example ofsuitable epoxy resins. They are obtainable by reacting a compound havingat least two carboxyl groups in the molecule with epichlorohydrin orglycerol dichlorohydrin or β-methylepichlorohydrin. The reaction isexpediently carried out in the presence of bases. The compounds havingat least two carboxyl groups in the molecule can in this case be, forexample, aliphatic polycarboxylic acids, such as glutaric acid, adipicacid, pimelic acid, suberic acid, azelaic acid, sebacic acid ordimerized or trimerized linoleic acid. Likewise, however, it is alsopossible to employ cycloaliphatic polycarboxylic acids, for exampletetrahydrophthalic acid, 4-methyltetrahydrophthalic acid,hexahydrophthalic acid or 4-methylhexahydrophthalic acid. It is alsopossible to use aromatic polycarboxylic acids such as, for example,phthalic acid, isophthalic acid, trimellitic acid or pyromellitic acid,or else carboxyl-terminated adducts, for example of trimellitic acid andpolyols, for example glycerol or 2,2-bis(4-hydroxycyclohexyl)propane,can be used.

Polyglycidyl ethers or poly(P-methylglycidyl) ethers obtainable byreacting a compound having at least two free alcoholic hydroxyl groupsand/or phenolic hydroxyl groups with a suitably substitutedepichlorohydrin under alkaline conditions or in the presence of anacidic catalyst followed by alkali treatment can likewise be used.Ethers of this type are derived, for example, from acyclic alcohols,such as ethylene glycol, diethylene glycol and higher poly(oxyethylene)glycols, propane-1,2-diol, or poly(oxypropylene) glycols,propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene) glycols,pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol,1,1,1-trimethylolpropane, bistrimethylolpropane, pentaerythritol,sorbitol, and from polyepichlorohydrins. Suitable glycidyl ethers canalso be obtained, however, from cycloaliphatic alcohols, such as 1,3- or1,4-dihydroxycyclohexane, bis(4-hydroxycyclo-hexyl)methane,2,2-bis(4-hydroxycyclohexyl)propane or1,1-bis(hydroxymethyl)cyclohex-3-ene, or they possess aromatic rings,such as N,N-bis(2-hydroxyethyl)aniline orp,p'-bis(2-hydroxyethylamino)diphenylmethane.

Particularly important representatives of polyglycidyl ethers orpoly(β-methylglycidyl) ethers are based on phenols; either on monocylicphenols, for example on resorcinol or hydroquinone, or on polycyclicphenols, for example on bis(4-hydroxyphenyl)methane (bisphenol F),2,2-bis(4-hydroxyphenyl)propane (bisphenol A), or on condensationproducts, obtained under acidic conditions, of phenols or cresols withformaldehyde, such as phenol novolaks and cresol novolaks. Thesecompounds are particularly preferred as epoxy resins for the presentinvention, especially diglycidyl ethers based on bisphenol A andbisphenol F and mixtures thereof.

Poly(N-glycidyl) compounds are likewise suitable for the purposes of thepresent invention and are obtainable, for example, bydehydrochlorination of the reaction products of epichlorohydrin withamines containing at least two amine hydrogen atoms. These amines may,for example, be n-butylamine, aniline, toluidine, m-xylylenediamine,bis(4-aminophenyl)methane or bis(4-methylaminophenyl)methane. However,other examples of poly(N-glycidyl) compounds include N,N'-diglycidylderivatives of cycloalkyleneureas, such as ethyleneurea or1,3-propyleneurea, and N,N'-diglycidyl derivatives of hydantoins, suchas of 5,5-dimethylhydantoin.

Poly(S-glycidyl) compounds are also suitable for component (A) of thenovel compositions, examples being di-S-glycidyl derivatives derivedfrom dithiols, for example ethane-1,2-dithiol orbis(4-mercaptomethylphenyl) ether.

Examples of epoxide compounds in which the epoxide groups form part ofan alicyclic or heterocyclic ring system includebis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentyl glycidyl ether,1,2-bis(2,3-epoxycyclopentyloxy)ethane, bis(4-hydroxycyclohexyl)methanediglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether,3,4-epoxycyclohexyl-methyl 3,4-epoxycyclohexanecarboxylate,3,4-epoxy-6-methyl-cyclohexylmethyl3,4-epoxy-6-methylcyclohexanecarboxylate, di(3,4-epoxycyclohexylmethyl)hexanedioate, di(3,4-epoxy-6-methylcyclohexylmethyl) hexanedioate,ethylenebis(3,4-epoxycyclohexane-carboxylate, ethanedioldi(3,4-epoxycyclohexylmethyl) ether, vinylcyclohexene dioxide,dicyclopentadiene diepoxide or2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,3-dioxane.

However, it is also possible to employ epoxy resins in which the1,2-epoxide groups are attached to different heteroatoms or functionalgroups. Examples of these compounds include the N,N,O--triglycidylderivative of 4-aminophenol, the glycidyl ether/glycidyl ester ofsalicylic acid,N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin or2-glycidyloxy-1,3-bis(5,5-dim ethyl-1-glycidylhydantoin-3-yl)propane.

Also conceivable is the use of liquid prereacted adducts of epoxyresins, such as those mentioned above, with hardeners for epoxy resins.

It is of course also possible to use liquid mixtures of epoxy resins inthe novel compositions.

As component (B) of the novel compositions it is possible to employ ahost of known and industrially tried and tested cationic photoinitiatorsfor epoxy resins. Examples of these are onium salts with anions of weaknucleophilicity. Examples thereof are halonium salts, iodosyl salts orsulfonium salts, as are described in EP-A-0 153 904, sulfoxonium salts,as described for example in EP-A-0 035 969, EP-A-0 044 274, EP-A-0 054509 and in EP-A-0 164 314, or diazonium salts, as described for examplein U.S. Pat. No. 3,708,296. Other cationic photoinitiators aremetallocene salts, as described for example in EP-A-0 094 914 and inEP-A-0 094 915.

An overview of further commonplace onium salt initiators and/ormetallocene salts is offered by "UV-Curing, Science and Technology",(Editor: S. P. Pappas, Technology Marketing Corp., 642 Westover Road,Stanford, Conn., USA) or "Chemistry & Technology of UV & EB Formulationsfor Coatings, Inks & Paints", Vol. 3 (edited by P. K. T. Oldring).

Preferred compositions are those comprising as component (B) a compoundof the formula (B-I), (B-II) or (B-III) ##STR1## in which R_(1B),R_(2B), R_(3B), R_(4B), R_(5B), R_(6B), and R_(7B) independently of oneanother are C₆ -C₁₈ aryl which is unsubstituted or substituted byappropriate radicals, and

A⁻ is CF₃ SO₃ ⁻ or an anion of the formula [LQ_(mB) ]⁻, where

L is boron, phosphorus, arsenic or antimony,

Q is a halogen atom, or some of the radicals Q in an anion LQ_(m) ⁻ mayalso be hydroxyl groups, and

mB is an integer corresponding to the valency of L enlarged by 1.

Examples of C₆ -C₁₈ aryl in this context are phenyl, naphthyl, anthryland phenanthryl. In these substituents present for appropriate radicalsare alkyl, preferably C₁ -C₆ alkyl, such as methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl or the variouspentyl or hexyl isomers, alkoxy, preferably C₁ -C₆ alkoxy, such asmethoxy, ethoxy, propoxy, butoxy, pentoxy or hexoxy, alkylthio,preferably C₁ -C₆ alkylthio, such as methylthio, ethylthio, propylthio,butylthio, pentylthio or hexylthio, halogen, such as fluorine, chlorine,bromine or iodine, amino groups, cyano groups, nitro groups or arylthio,such as phenylthio. Examples of preferred halogen atoms Q are chlorineand, in particular, fluorine. Preferred anions LQ_(mB) are BF₄ ⁻, PF₆ ⁻,AsF₆ ⁻, SbF₆ ⁻ and SbF₅ (OH)⁻.

Particularly preferred compositions are those comprising as component(B) a compound of the formula (B-III), in which R_(5B), R_(6B) andR_(7B) are aryl, aryi being in particular phenyl or biphenyl or mixturesof these two groups.

Further preferred compositions are those comprising as component (B) acompound of the formula (B-IV) ##STR2## in which cB is 1 or 2,

dB is1, 2, 3, 4or5,

X_(B) is a non-nucleophilic anion, especially PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, CF₃SO₃ ⁻, C₂ F₅ SO₃ ⁻, n-C₃ F₇ SO₃ ⁻, n-C₄ F₉ SO₃ ⁻, n-C₆ F₁₃ SO₃ ⁻ andn-C₈ F₁₇ SO₃ ⁻,

R_(8B) is a π-arene and

R_(9B) is an anion of a π-arene, especially a cyclopentadienyl anion.

Examples of 7u-arenes as R_(8B) and anions of π-arenes as R_(9B) can befound in EP-A-0 094 915. Examples of preferred π-arenes as R_(8B) aretoluene, xylene, ethylbenzene, cumene, methoxybenzene,methyinaphthalene, pyrene, perylene, stilbene, diphenylene oxide anddiphenylene sulfide. Cumene, methylnaphthalene or stilbene areparticularly preferred. Examples of non-nucleophilic anions X⁻ are FSO₃⁻, anions of organic sulfonic acids, of carboxylic acids or of anionsLQ_(mB) ⁻. Preferred anions are derived from partially fluoro- orperfluoro-aliphatic or partially fluoro- or perfluoro-aromaticcarboxylic acids such as CF₃ SO₃ ⁻, C₂ F₅ SO₃ ⁻, n-C₃ F₇ SO₃ ⁻, n-C₄ F₉SO₃ ⁻, n-C₆ F₁₃ SO₃ ⁻, n-C₈ F₁₇ SO₃ ⁻, or in particular from partiallyfluoro- or perfluoro-aliphatic or partially fluoro- orperfluoro-aromatic organic sulfonic acids, for example from C₆ F₅ SO₃ ⁻,or preferably are anions LQ_(mB) ⁻, such as BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆⁻, and SbF₅ (OH)⁻. Preference is given to PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, CF₃ SO₃⁻, C₂ F₅ SO₃ ⁻, n-C₃ F₇ SO₃ ⁻, n-C₄ F₉ SO₃ ⁻, n-C₆ F₁₃ SO₃ ⁻, n-C₈ F₁₇SO₃ ⁻.

The metallocene salts can also be employed in combination with oxidizingagents. Such combinations are described in EP-A-0 126 712.

In order to increase the light yield it is possible, depending on thetype of initiator, also to employ sensitizers. Examples of these arepolycyclic aromatic hydrocarbons or aromatic keto compounds. Specificexamples of preferred sensitizers are mentioned in EP-A-0 153 904.

In the novel compositions it is possible as component (C) to employ alltypes of photoinitiators which form free radicals given the appropriateirradiation. Typical representatives of free-radical photoinitiators arebenzoins, such as benzoin, benzoin ethers, such as benzoin methyl ether,benzoin ethyl ether and benzoin isopropyl ether, benzoin phenyl etherand benzoin acetate, acetophenones, such as acetophenone,2,2-dimethoxy-acetophenone and 1,1-dichloroacetophenone, benzil, benzilketals, such as benzil dimethylketal and benzil diethyl ketal,anthraquinones, such as 2-methylanthraquinone, 2-ethylanthra-quinone,2-tert-butylanthraquinone, 1-chloroanthraquinone and2-amylanthraquinone, and also triphenylphosphine, benzoylphosphineoxides, for example 2,4,6-trimethylbenzoyl-diphenylphosphine oxide(Luzirin® TPO), bisacylphosphine oxides, benzophenones, such asbenzophenone and 4,4'-bis(N,N'-dimethylamino)benzophenone, thioxanthonesand xanthones, acridine derivatives, phenazine derivatives, quinoxalinederivatives or 1-phenyl-1,2-propanedione 2--O--benzoyl oxime,1-aminophenyl ketones or 1-hydroxy phenyl ketones, such as1-hydroxycyclohexyl phenyl ketone, phenyl 1-hydroxyisopropyl ketone and4-isopropylphenyl 1-hydroxyisopropyl ketone, all of which constituteknown compounds.

Particularly suitable free-radical photoinitiators which are usedcustomarily in combination with an He/Cd laser as light source areacetophenones, such as 2,2-dialkoxybenzophenones and 1-hydroxy phenylketones, for example 1-hydroxycyclohexyl phenyl ketone or2-hydroxy-isopropyl phenyl ketone (=2-hydroxy-2,2-dimethylacetophenone),but especially 1-hydroxy-cyclohexyl phenyl ketone.

A class of photoinitiators (C) which is commonly employed when usingargon ion lasers comprises the benzil ketals, for example benzildimethyl ketal. In particular, the photoinitiator used is an a-hydroxyphenyl ketone, benzil dimethyl ketal or2,4,6-trimethylbenzoyldiphenyl-phosphine oxide.

A further class of suitable photoinitiators (C) is constituted by theionic dye-counterion compounds, which are capable of absorbing actinicradiation and of generating free radicals which are able to initiate thepolymerization of the acrylates. The novel compositions containing ionicdye-counterion compounds can in this way be cured more variably withvisible light in an adjustable wavelength range of 400-700 nm. Ionicdye-counterion compounds and their mode of action are known, for examplefrom EP-A-0 223 587 and U.S. Pat. Nos. 4,751,102, 4,772,530 and4,772,541. Examples of suitable ionic dye-counterion compounds are theanionic dye-iodonium ion complexes, the anionic dye-pyryllium ioncomplexes and, in particular, the cationic dye-borate anion compounds ofthe following formula ##STR3## in which D_(c) ⁺ is a cationic dye andR_(1C), R_(2C), R_(3C) and R_(4C) independently of one another are eachan alkyl, aryl, alkaryl, allyl, aralkyl, alkenyl, alkynyl, an alicyclicor saturated or unsaturated heterocyclic group. Preferred definitionsfor the radicals R_(1C) to R_(4C) can be taken for example, from EP-A-0223 587.

As photoinitiator (C) the novel compositions preferably include a1-hydroxy phenyl ketone, especially 1-hydroxycyclohexyl phenyl ketone.

The photoinitiators (B) and (C) are added in effective quantities, i.e.in quantities from 0.1 to 10, particularly from 0.5 to 5 percent byweight, based on the overall quantity of the composition. If the novelcompositions are used for stereolithographic processes, in which laserbeams are normally employed, it is essential for the absorption capacityof the composition to be matched, by way of the type and concentrationof the photoinitiators, in such a way that the depth of curing at normallaser rate is from approximately 0.1 to 2.5 mm. The overall quantity ofphotoinitiators in the novel compositions is preferably between 0.5 and6 percent by weight.

The novel mixtures may also contain various photoinitiators of differentsensitivity to radiation of emission lines with different wavelengths.What is achieved by this is, for example, a better utilization of aUV/VIS light source which emits emission lines of different wavelengths.In this context it is advantageous for the various photoinitiators to beselected such, and employed in a concentration such, that equal opticalabsorption is produced with the emission lines used.

The novel compositions preferably comprise component (D) in a quantityof at least 5 percent by weight, in particular at least 10 percent byweight, based on the overall quantity of components (A), (B), (C), (D)and (E).

Component (D) of the novel compositions is preferably from the groupconsisting of

(D1) the dihydroxybenzenes, trihydroxybenzenes and the compounds of theformula (D-I): ##STR4## in which R_(1D) and R_(2D) are a hydrogen atomor a methyl group; (D2) the compounds of the formula (D-II): ##STR5## inwhich R_(1D) and R_(2D) are each a hydrogen atom or a methyl group;

R_(3D) and R_(4D) are all, independently of one another, a hydrogen atomor a methyl group, and

xD and yD are each an integer from 1 to 15;

(D3) trimethylolpropane, glycerol, castor oil and the compounds of theformula (D-III) and (D-IV): ##STR6## in which R_(5D) is an unbranched orbranched (zD)-valent C₂ -C₂₀ alkane residue,

preferably a (zD)-valent C₂ -C₆ alkane residue,

all radicals R_(6D), independently of one another, are a hydrogen atomor a methyl group,

zD is an integer from 1 to 4 and

vD is an integer from 2 to 20; and also

(D4) the compounds of the formulae (D-V), (D-VI), (D-VII), (D-VIII)(D-IX) and (D-X): ##STR7## in which R_(7D), R_(9D) and R_(10D) are eacha hydrogen atom or a methyl group and each R_(8D) is a group selectedfrom the groups of the formulae (D-XI), (D-XII), (D-XIII) and (D-XIV):##STR8##

The compounds of the above formulae (D-I), (D-II), (D-V), (D-VI) and(D-IX) are preferably the respective 1,4 derivatives or bis-1,4derivatives.

The compounds of the formulae (D-I) to (D-X) and methods for theirpreparation are known to the person skilled in the art.

Component (D) of the novel compositions preferably consists of (D2)phenolic compounds having at least 2 hydroxyl groups which are reactedwith ethylene oxide, propylene oxide or with ethylene oxide andpropylene oxide, and especially of the compounds of the formula (D-IIa):##STR9## in which R_(1D) and R_(2D) are both a hydrogen atom or both amethyl group;

R_(3D) and R_(4D) are all, independently of one another, each a hydrogenatom or a methyl group, and

xD and yD are each an integer from 1 to 15.

The liquid poly(meth)acrylates having a (meth)acrylate functionality ofmore than two which are used in the novel compositions as component (E)may, for example, be tri-, tetra- or pentafunctional monomeric oroligomeric aliphatic, cycloaliphatic or aromatic acrylates ormethacrylates. The compounds preferably have a molecular weight of from200 to 500.

Examples of suitable aliphatic polyfunctional (meth)acrylates are thetriacrylates and trimethacrylates of hexane-2,4,6-triol, glycerol or1,1,1-trimethylolpropane, ethoxylated or propoxylated glycerol or1,1,1-trimethylolpropane, and the hydroxyl-containing tri(meth)acrylateswhich are obtained by reacting triepoxide compounds, for example thetriglycidyl ethers of said triols, with (meth)acrylic acid. It is alsopossible to use, for example, pentaerythritol tetraacrylate,bistrimethylolpropane tetraacrylate, pentaerythritolmonohydroxytriacrylate or -methacrylate, or dipentaerythritolmonohydroxypentaacrylate or -methacrylate.

It is additionally possible, for example, to use polyfunctional urethaneacrylates or urethane methacrylates. These urethane (meth)acrylates areknown to the person skilled in the art and can be prepared in a knownmanner by, for example, reacting a hydroxyl-terminated polyurethane withacrylic acid or methacrylic acid, or by reacting anisocyanate-terminated prepolymer with hydroxyalkyl (meth)acrylates togive the urethane (meth)acrylate.

Examples of suitable aromatic tri(meth)acrylates are the reactionproducts of triglycidyl ethers of trihydric phenols and phenol or cresolnovolaks containing three hydroxyl groups, with (meth)acrylic acid.

The (meth)acrylates employed as component (E) are known compounds andsome are commercially available, for example from the SARTOMER Companyunder product designations such as SR®295, SR®350, SR®351, SR®367,SR®399, SR®444, SR®454 or SR®9041.

Preferred compositions are those in which component (E) is atri(meth)acrylate or a penta(meth)acrylate.

Suitable examples of the di(meth)acrylate component (F) are thedi(meth)acrylates of cycloaliphatic or aromatic diols such as1,4-dihydroxymethylcyclohexane, 2,2-bis(4-hydroxy-cyclohexyl)propane,bis(4-hydroxycyclohexyl)methane, hydroquinone, 4,4'-dihydroxybi-phenyl,bisphenol A, bisphenol F, bisphenol S, ethoxylated or propoxylatedbisphenol A, ethoxylated or propoxylated bisphenol F or ethoxylated orpropoxylated bisphenol S. Di(meth)acrylates of this kind are known andsome are commercially available.

Other di(meth)acrylates which can be employed are compounds of theformulae (F-I), (F-II), (F-III) or (F-IV) ##STR10## in which R_(1F) is ahydrogen atom or methyl,

Y_(F) is a direct bond, C₁ -C₆ alkylene, --S--, --O--, --SO--, --SO₂ --or --CO--,

R_(2F) is a C₁ -C₈ alkyl group, a phenyl group which is unsubstituted orsubstituted by one or more C₁ -C₄ alkyl groups, hydroxyl groups orhalogen atoms, or is a radical of the formula --CH₂ --OR_(3F) in which

R_(3F) is a C₁ -C₈ alkyl group or phenyl group, and

AF is a radical selected from the radicals of the formulae ##STR11##

Further examples of possible di(meth)acrylates are compounds of theformulae (F-V), (F-VI), (F-VII) and (F-VIII) ##STR12##

These compounds of the formulae (F-I) to (F-VIII) are known and some arecommercially available. Their preparation is also described in EP-A-0646 580.

In many cases it is also expedient to add further constituents to thenovel compositions, examples being customary additives, such as reactivediluents, for example propylene carbonate, propylene carbonate propenylether or lactones, stabilizers, for example, UV stabilizers,polymerization inhibitors, release agents, wetting agents, levellingagents, sensitizers, antisettling agents, surface-active agents, dyes,pigments or fillers. Each of these is employed in a quantity effectivefor the desired purpose, and together they make up preferably up to 20percent by weight of the novel compositions. Fillers in particular,however, may also be sensibly employed in greater quantities, forexample in quantities of up to 75 percent by weight.

Particularly preferred novel compositions are those in which bothcomponent (A) and component (D) comprise substances having aromaticcarbon rings in their molecule. In such compositions, component (A)preferably contains one or more aromatic glycidyl ethers, especiallydiglycidyl ethers based on bisphenols, especially based on bisphenol A,bisphenol F, and mixtures of such diglycidyl ethers.

Particularly good properties are had by novel compositions comprising:

(A1) from 20 to 60 percent by weight of an aromatic difunctional or morehighly functional polyglycidyl ether or of a liquid mixture consistingof aromatic difunctional or more highly functional polyglycidyl ethers;

(A2) from 0 to 50 percent by weight of an aliphatic or cycloaliphaticdifunctional or more highly functional glycidyl ether;

(B) from 0.1 to 10 percent by weight of a cationic photoinitiator or ofa mixture of cationic photoinitiators; and

(C) from 0.1 to 10 percent by weight of a free-radical photoinitiator orof a mixture of free-radical photoinitiators;

(D) from 5 to 40 percent by weight of a phenolic compound having atleast 2 hydroxyl groups and/or of a phenolic compound having at least 2hydroxyl groups which is reacted with ethylene oxide, propylene oxide orwith ethylene oxide and propylene oxide;

(E) from 4 to 30 percent by weight of at least one liquidpoly(meth)acrylate having a (meth)acrylate functionality of more than 2,

(F) from 0 to 20 percent by weight of one or more di(meth)acrylates and

(G) from 0 to 10 percent by weight of a reactive diluent.

A further particularly preferred composition according to the inventioncomprises:

(A) from 40 to 80 percent by weight of an aliphatic and/orcycloaliphatic difunctional or more highly functional glycidyl ether orof a mixture of such resins;

(B) 2 to 5 percent by weight of a cationic photoinitiator or of amixture of cationic photoinitiators, particularly of a sulfonium typephotoinitiator;

(C) 0.5 to 2 percent by weight of a free-radical photoinitiator or of amixture of free-radical photoinitiators, particularly of a 1-hydroxyphenyl ketone;

(D) from 10 to 20 percent by weight of a phenolic compound having atleast 2 hydroxyl groups which is reacted with ethylene oxide, withpropylene oxide or with ethylene oxide and propylene oxide;

(E) from 4 to 10 percent by weight of at least one liquidpoly(meth)acrylate having a (meth)acrylate functionality of more than 2,and

(F) from 4 to 10 percent by weight of one or more di(meth)acrylates.

The novel compositions can be prepared in a known manner by, forexample, premixing individual components and then mixing these premixes,or by mixing all of the components using customary devices, such asstirred vessels, in the absence of light and, if desired, at slightlyelevated temperature.

The novel compositions can be polymerized by irradiation with actiniclight, for example by means of electron beams, X-rays, UV or VIS light,preferably with radiation in the wavelength range of 280-650 nm.Particularly suitable are laser beams of HeCd, argon or nitrogen andalso metal vapour and NdYAG lasers. The person skilled in the art isaware that it is necessary, for each chosen light source, to select theappropriate photoinitiator and, if appropriate, to carry outsensitization. It has been recognized that the depth of penetration ofthe radiation into the composition to be polymerized, and also theoperating rate, are directly proportional to the absorption coefficientand to the concentration of the photoinitiator. In stereolithography itis preferred to employ those photoinitiators which give rise to thehighest number of forming free radicals or cationic particles and whichenable the greatest depth of penetration of the radiation into thecompositions which are to be polymerized.

The invention additionally relates to a method of producing a curedproduct, in which compositions as described above are treated withactinic radiation. For example, it is possible in this context to usethe novel compositions as adhesives, as coating compositions, asphotoresists, for example as solder resists, or for rapid prototyping,but especially for stereolithography. When the novel mixtures areemployed as coating compositions, the resulting coatings on wood, paper,metal, ceramic or other surfaces are clear and hard. The coatingthickness may vary greatly and can for instance be from 0.01 mm to about1 mm. Using the novel mixtures it is possible to produce relief imagesfor printed circuits or printing plates directly by irradiation of themixtures, for example by means of a computer-controlled laser beam ofappropriate wavelength or employing a photomask and an appropriate lightsource.

One specific embodiment of the abovementioned method is a process forthe stereolithographic production of a three-dimensional shaped article,in which the article is built up from a novel composition with the aidof a repeating, alternating sequence of steps (a) and (b); in step (a),a layer of the composition, one boundary of which is the surface of thecomposition, is cured with the aid of appropriate radiation within asurface region which corresponds to the desired cross-sectional area ofthe three-dimensional article to be formed, at the height of this layer,and in step (b) the freshly cured layer is covered with a new layer ofthe liquid, radiation-curable composition, this sequence of steps (a)and (b) being repeated until an article having the desired shape isformed. In this process, the radiation source used is preferably a laserbeam, which with particular preference is computer-controlled.

In general, the above-described initial radiation curing, in the courseof which the so-called green models are obtained which do not as yetexhibit adequate strength, is followed then by the final curing of theshaped articles by heating and/or further irradiation.

The term "liquid" in this application is to be equated with "liquid atroom temperature" in the absence of any statement to the contrary, roomtemperature being understood as being, in general, a temperature between5° and 40° C., preferably between 10° and 30° C.

EXAMPLES

The trade names of the components as indicated in the examples belowcorrespond to the chemical substances as defined in the following table.

    ______________________________________                                        Trade name                                                                             Chemical designation                                                 ______________________________________                                        Araldit GY 250                                                                         bisphenol A diglycidyl ether                                           Araldit PY 306 bisphenol F diglycidyl ether                                   Araldit CY 179 3,4-epoxycyclohexylmethyl                                       3',4'-epoxycyclohexanecarboxylate                                            Araldit DY 026 butanediol diglycidyl ether                                    Araldit DY trimethylolpropane triglycidyl ether                               0395                                                                          Araldit DY cyclohexanedimethanol diglycidyl ether                             0396                                                                          Cyracure UVI mixture of (C.sub.6 H.sub.5)S(C.sub.6 H.sub.4)--S.sup.+                 (C.sub.6 H.sub.5).sub.2 SbF.sub.6.sup.- and                            6974 F.sub.6 Sb.sup.- (C.sub.6 H.sub.5).sub.2 S.sup.+ --(C.sub.6                     H.sub.4)S(C.sub.6 H.sub.4)--S.sup.+ (C.sub.6 H.sub.5).sub.2                   SbF.sub.6                                                              Irgacure 184 1-hydroxycyclohexyl phenyl ketone                                Dianol 320 propoxylated bisphenol A                                           Dianol 2211 ethoxylated bisphenol A                                           Sartomer SR dipentaerythritol monohydroxypentaacrylate                        399                                                                           Sartomer SR                                                                   9041                                                                          Novacure 3700 bisphenol A diglycidyl ether diacrylate                         Sartomer SR dimethacrylate of ethoxylated bisphenol A                         348                                                                           Pleximon neopentylglycol dimethacrylate                                       V 773                                                                         Sartomer SR hexanediol diacrylate                                             238                                                                         ______________________________________                                    

The formulations indicated in the examples are prepared by mixing thecomponents, with a stirrer at 60° C., until a homogeneous composition isobtained. The physical data relating to the formulations are obtained asfollows:

The viscosity of the liquid mixture is determined at 30° C. using aBrookfield viscometer.

The mechanical properties of the formulations are determined onthree-dimensional specimens produced with the aid of an He/Cd or Ar/UVlaser.

The photosensitivity of the formulations is determined on so-calledwindow panes. In this determination, single-layer test specimens areproduced using different laser energies, and the layer thicknessesobtained are measured. The plotting of the resulting layer thickness ona graph against the logarithm of the irradiation energy used gives a"working curve". The slope of this curve is termed Dp (given in mm ormils). The energy value at which the curve passes through the x-axis istermed Ec (and is the energy at which gelling of the material still justtakes place; cf. P. Jacobs, Rapid Prototyping and Manufacturing, Soc. ofManufacturing Engineers, 1992, p. 270 ff.).

The green strength is determined by measuring the flexural modulus 10minutes and 1 hour after production of the test specimen (ASTM D 790).The flexural modulus after curing is determined after the test specimenhas been cured in UV light for 1 hour.

The curl factor (CF) is used in stereolithography in order to comparethe shrinkage properties of different formulations (cf. P. Jacobs, RapidPrototyping and Manufacturing, Soc. of Manufacturing Engineers, 1992, p.256 ff.). The curl factors (in %) given in this application aredetermined on test specimens produced using the "ACES" structural design(cf. P. Jacobs, Stereolithography and other RP&M Technologies, Soc. ofManufacturing Engineers, 1996, p.156 ff.) and with a layer thickness of0.15 mm (6 mils).

To determine the water uptake, test specimens are produced using the"quick cast" structural design (cf. P. Jacobs, Stereolithography andother RP&M Technologies, 1996, p. 183 ff.) and after complete curing (60minutes under UV light, 30 minutes at 100° C.) are dried to constantweight in a desiccator. The samples are then stored at 62 and 88%atmospheric humidity. The water uptake is determined by weighing thesamples at regular intervals until constant weight is reached, which isgenerally the case after no more than 7-14 days. In these examples, thewater uptake after 14 days is given.

Example 1

a) The following components are used as indicated above to produce ahomogeneous liquid composition:

    ______________________________________                                        14.6          g of Araldit DY 0395                                              42.5 g of Araldit CY 179                                                      6.0 g of Novacure 3700                                                        6.0 g of Sartomer 399                                                         24.9 g of Dianol 320                                                          2.0 g of Irgacure 184                                                         4.0 g of Cyracure UVI 6974                                                  ______________________________________                                    

The viscosity of this mixture is 800 mPa s (cps) at 30° C.

The slope of the "working curve" is 0.124 mm (4.9 mils); the criticalenergy Ec is 12.5 J/cm².

The flexural modulus of the green model one hour after production in thestereolithography unit is 61 MPa, and after complete curing is 2360 MPa.

The curl factor is 8.5%.

The water uptake of a quick-cast test specimen after 14 days at 62% rel.atmospheric humidity is 2.1% and is 4.4% after 14 days at 88%atmospheric humidity.

b) A composition comprising the following components:

    ______________________________________                                        20.0       g of Araldit DY 0395                                                 15.0 g of Araldit DY 0396                                                     34.0 g of Araldit CY 179                                                      6.0 g of Bisphenol A diglycidyl diacrylate                                    6.0 g of Sartomer 9041                                                        13.5 g of Dianol 320                                                          1.5 g of Irgacure 184                                                         4.0 g of Cyracure UVI 6974                                                  ______________________________________                                    

shows properties comparable to those found for the composition describedunder a).

Examples 2-8

The mixtures are prepared as described above. Their compositions andphysical properties can be taken from the table below.

    __________________________________________________________________________    Component                Ex. 2                                                                              Ex. 3 Ex. 4                                                                              Ex. 5 Ex. 6                                                                              Ex. 7                                                                              Ex. 8                __________________________________________________________________________    Araldit GY 250                                                                              (A)                              22   22    22                    Araldit PY 306 (A)     23 25 20                                               Araldit CY 179 (A) 42.5 48 65 65                                              Araldit DY 026 (A) 14.6                                                       Araldit DY 0395 (A)  17.5                                                     Araldit DY 0396 (A)     10 5 10                                               Cyracure UVI 6974 (B) 4 3 0.5 0.5 4 4 4                                       Irgacure 184 (C) 2 0.5 2.5 2.5 1 1 1                                          Bisphenol A (D)    20                                                         Dianol 320 (D) 24.9 18.9   10 10 15                                           Dianol 2211 (D)   20                                                          Sartomer SR 399 (E) 6 6 6 6 10 10 10                                          Novacure 3700 (F) 6 6 6 6                                                     Sartomer SR 348 (F)     10 10 10                                              Pleximon V 773 (F)     10                                                     Sartomer SR 238 (F)      8 8                                                  pyrene additive  0.1                                                          propylenecarbonate additive      5                                          viscosity (30° C.) [mPa s (cps)]                                                                431  563   755  3350  516  346   581                   laser used Ar/UV Ar/UV HeCd HeCd Ar/UV Ar/UV Ar/UV                            Dp [mm (converted from the indication in mils)] 0.120 0.132 0.128 0.112                                                               .121 0.100                                                                    0.134                 Ec [mJ/cm.sup.2 ] 12.2 29.39 15.93 18.02 34.94 25.82 38.3                     Flex. modulus of the green model after 10 min [MPa] 0 86 247 90 395 300                                                               663                   Flex. modulus of the green model after 60 min [MPa] 177 348   1024 993                                                                1087                  Flex. modulus of the test specimen after 60 min UV [MPa] 2370 1621                                                                    2118 2216 3141                                                                 curl factor 6                                                                ACES [%] 7 8.8                                                                7.5 12 7.7 11.5                                                               17                    Water uptake [%], quick-cast strips (cured: 1 h, UV + 2.1 2.1 2.3  1.2                                                                1.2 1.2                                                                        30 min/100.degr                                                              ee. C.), 14 d                                                                 at 62% atmospher                                                              ic humidity                                                                    Water uptake                                                                 [%], quick-cast                                                               strips (cured:                                                                1 h, UV + 4.3                                                                 3.9 4.7  2.2                                                                  2.2 2.2                                                                        30 min/100.degr                                                              ee. C.), 14 d                                                                 at 88% atmospher                                                              ic humidity         __________________________________________________________________________

Example 9-11

These examples show how components of type (D4) having OH groups andepoxy groups can be prepared.

Example 9: Preparation of a compound of the formula ##STR13## 56.06 g(0.5 mol) of tetrahydrobenzyl alcohol are heated with 0.24 g of borontrifluoride ethyl etherate to 60° C. Then 75.09 g (0.5 mol) of phenylglycidyl ether are added dropwise, the temperature being maintained at60° C. using an ice bath. Stirring is continued for about 2 hours. Then6.6 g of Florisil (magnesium silicate, adsorbent) are added, and themixture is filtered while still hot. 100 g (0.38 mol) of the resultingproduct are dissolved in 240 ml of chloroform. Then 196 g of 8% hydrogenperoxide (0.46 mol), 3 g of Aliquat 336 (tricaprylmethylammoniumchloride), 6.2 g of sodium tungstate dihydrate and 3.8 g of phosphoricacid are added. The mixture is refluxed with stirring. After about 1hour the mixture is cooled and the organic phase is isolated, washedwith water and dried. Evaporation of the solvent gives 85.65 g (81%) ofa viscous yellow liquid having an epoxide content of 3.59 eq/kg (65% oftheory).

Example 10: Preparation of a compound of the formula ##STR14## 250 g(2.23 mol) of tetrahydrobenzyl alcohol are heated with 1.2 g of borontrifluoride ethyl etherate to 60° C. Then 415.46 g (1.12 mol) ofbisphenol A diglycidyl ether (Araldit GY 250) are added dropwise, thetemperature being maintained at about 60° C. After the end of theaddition, 33.3 g of Florisil are added, and the mixture is diluted withchloroform and filtered. The organic phase is washed twice with waterand dried and the solvent is stripped off on a rotary evaporator. 73.42g (0.13 mol) of the resulting product are dissolved in 150 ml ofchloroform. Then 131.8 g (0.31 mol) of 8% hydrogen peroxide, 1.17 g ofAliquat 336, 2.13 g of sodium tungstate dihydrate and 1.27 g ofphosphoric acid are added. The mixture is refluxed with stirring forabout 6 hours. Then the organic phase is separated off, washed withwater and dried and the solvent is stripped off on a rotary evaporator.Yield: 64.9 g (83.6%), epoxide content 2.1 eq/kg (63.4% of theory)

Example 11: Preparation of a compound of the formula ##STR15## 87.13 g(0.58 mol) of TCD Alkohol E* (Hoechst, unsaturated tricyclohexylalcohol) are heated with 0.34 g of boron trifluoride ethyl etherate to60° C. Then 100 g (0.29 mol) of bisphenol A diglycidyl ether (Araldit GY250) are added dropwise, the temperature being maintained at 60° C.After the end of the addition, the mixture is stirred for about 2 hoursmore. Then 9.4 g of Florisil are added, and the mixture is diluted withchloroform and filtered. The organic phase is washed and dried, and thesolvent is stripped off on a rotary evaporator. 185 g (0.29 mol) of theresulting product are dissolved in 300 ml of chloroform. Then 295.9 g(0.7 mol) of 8% hydrogen peroxide, 2.62 g of Aliquat 336, 4.75 g ofsodium tungstate hydrate and 2.84 g of phosphoric acid are added. Themixture is stirred at 60° C. for about 5 hours. The organic phase isthen separated off, washed with water and dried, and the solvent isstripped off on a rotary evaporator.

Yield: 194.2 g (99%), epoxide content 2.35 eq/kg (79.3% of theory).##STR16##

Examples 12-15

The mixtures are prepared as described above. Their compositions andphysical properties are shown in the table below.

    __________________________________________________________________________    Component                Ex. 12                                                                            Ex. 13                                                                            Ex. 14                                                                            Ex. 15                                   __________________________________________________________________________    Araldit GY 250                                                                              (A)        20  48  25  26                                         Araldit PY 306 (A) 22  25 26                                                  Araldit DY 0395 (A) 15 20 15 15                                               Cyracure UVI 6974 (B) 4 1 4 4                                                 Irgacure 184 (C) 1 1 1 1                                                      Dianol 320 (D) 10                                                             Castor oil (D)  10 10                                                         1,6-Hexanediol (D)    8                                                       Compound of Ex. 9 (D) 8                                                       Sartomer SR 399 (E) 10 10 10                                                  Novacure 3700 (F) 10 10 10 10                                               viscosity (30° C.) [mPa s (cps)]                                                                5810                                                                              1030                                                                              3770                                                                              1210                                       laser used Ar/UV He/Cd Ar/UV Ar/UV                                            Dp [mm (converted from the indication in mils)] 3.73 3.49 4.37 3.78                                               Ec [mJ/cm.sup.2 ] 25.91 19.23 30.33                                          16.7                                       Flex. modulus of the green model after 10 min [MPa]  0 200                    Flex. modulus of the green model after 60 min [MPa]  110 394                  Flex. modulus of the test specimen after 60 min UV [MPa] 626 955 2159                                            1917                                       curl factor 6 ACES [%] 4.5 18 9.8 20.8                                        Water uptake [%], quick-cast strips (cured: 1 h, UV + 1.4 1 1.1 1.6                                               30 min/100° C.), 14 d at 62%                                          atmospheric humidity                       Water uptake [%], quick-cast strips (cured: 1 h, UV + 2.8 1.6 2.1 3                                               30 min/100° C.), 14 d at 88%                                          atmospheric humidity                     __________________________________________________________________________

What is claimed is:
 1. A liquid, radiation-curable composition which inaddition to a liquid, free-radically polymerizable component comprisesat least the following additional components:(A) from 40 to 80 percentby weight of a liquid epoxy resin having two or more then two epoxygroups per molecule or of a liquid mixture consisting of epoxy resinshaving two or more than two epoxy resins per molecule; (B) from 0.1 to10 percent by weight of a cationic photoinitiator or of a mixture ofcationic photoinitiators; and (C) from 0.1 to 10 percent by weight of afree-radical photoinitiator or of a mixture of free-radicalphotoinitiators; and (D) up to 40 percent by weight of a hydroxycompound, in which composition component (D) is selected from the groupconsisting of:(D1) a phenolic compound having at least 2 hydroxyl groupsselected from the group consisting of the dihydroxybenzenes,trihydroxybenzenes and the compounds of the formula (D-I): ##STR17## inwhich R_(1D) and R_(2D) are a hydrogen atom or a methyl group; (D2) aphenolic compound having at least 2 hydroxyl groups, which have beenreacted with ethylene oxide, proplyene oxide or with ethylene oxide andpropylene oxide, which phenolic compound is selected from the groupconsisting of the compounds of the formula (D-II): ##STR18## in whichR_(1D) and R_(2D) are each a hydrogen atom or a methyl group; R_(3D) andR_(4D) are all, independently of one another, a hydrogen atom or amethyl group, and xD and yD are each an integer from 1 to 15; (D3) analiphatic hydroxy compound having not more than 80 carbon atoms selectedfrom the group consisting of trimethylolpropane, glycerol, castor oiland the compounds of the formula (D-III) and (D-IV): ##STR19## in whichR_(5D) is an unbranched or branched (zD)-vatent C₂ -C₂₀ alkane residue,all radicals R_(6D), independently of one another, are a hydrogen atomor a methyl group, zD is an integer from 1 to 4 and vD is an integerfrom 2 to 20; (D4) a compound having at least one hydroxyl group and atleast one epoxide group which is selected from the group consisting ofthe compounds of the formulae (D-V), (D-VI), (D-VII), (D-VIII) (D-IX)and (D-X): ##STR20## in which R_(7D), R_(9D) and R_(10D) are each ahydrogen atom or a methyl group and each R_(8D) is a group selected fromthe groups of the formulae (D-XI), (D-XII), (D-XIII) and (D-XIV):##STR21## (D5) a mixture of at least 2 of the compounds mentioned under(D1) to (D4), wherein component (D) is present in the composition in aquantity of at least 2 percent by weight; the free-radicallypolymerizable component comprises at least (E) from 4 to 30 percent byweight of at least one liquid poly(meth)acrylate having a (meth)acrylatefunctionality of more than 2; and at least one of components (A) and (D)comprises a substance which has aromatic carbon rings in its molecule.2. A composition according to claim 1, which contains at least 5 percentby weight of component (D).
 3. Composition according to claim 1, inwhich component (D) consists of (D2) phenolic compounds having at least2 hydroxyl groups which are reacted with ethylene oxide, propylene oxideor with ethylene oxide and propylene oxide.
 4. Composition according toclaim 3, in which component (D) consists of (D2) the compounds of theformula (D-IIa) ##STR22## in which R_(1D) and R_(2D) are both a hydrogenatom or a methyl group; R_(3D) and R_(4D) are all, independently of oneanother, a hydrogen atom or a methyl group, andxD and yD are each aninteger from 1 to
 15. 5. A composition according to claim 1, which as anadditional component (F) contains one or more di(meth)acrylates.
 6. Acomposition according to claim 5, which contains component (F) in aquantity of from 5 to 40 percent by weight.
 7. A composition accordingto claim 1, in which both component (A) and component (D) comprisesubstances having aromatic carbon rings in their molecule.
 8. Acomposition according to claim 1, comprising(A1) from 20 to 60 percentby weight of an aromatic polyglycidyl ether having two or more than twoglycidylether groups per molecule or of a liquid mixture consisting ofaromatic polyglycidyl ethers having two or more than two alycidylethergroups per molecule; (A2) from 0 to 50 percent by weight of an aliphaticor cycloaliphatic glycidyl ether; (B) from 0.1 to 10 percent by weightof a cationic photoinitiator or of a mixture of cationicphotoinitiators; and (C) from 0.1 to 10 percent by weight of afree-radical photoinitiator or of a mixture of freeradicalphotoinitiators; (D) from 5 to 40 percent by weight of a phenoliccompound having at least 2 hydroxyl groups and/or of a phenolic compoundhaving at least 2 hydroxyl groups which is reacted with ethylene oxide,propylene oxide or with ethylene oxide and propylene oxide; (E) from 4to 30 percent by weight of at least one liquid poly(meth)acrylate havinga (meth)acrylate functionality of more than 2, (F) from 0 to 20 percentby weight of one or more di(meth)acrylates and (G) from 0 to 10 percentby weight of a reactive diluent.
 9. A composition according to claim 1,comprising:(A) from 40 to 80 percent by weight of an aliphatic and/orcycloaliphatic glycidyl ether having two or more than two glycidvlethergroups per molecule or of a mixture of such resins; (B) 2 to 5 percentby weight of a cationic photoinitiator or of a mixture of catonicphotoinitiators; (C) 0.5 to 2 percent by weight of a free-radicalphotoinitiator or of a mixture of free-radical photoinitators; (D) from10 to 20 percent by weight of a phenolic compound having at least 2hydroxyl groups which is reacted with ethylene oxide, with propyleneoxide or with ethylene oxide and propylene oxide; (E) from 4 to 10percent by weight of at least one liquid poly(meth)acrylate having a(methyacrylate functionality of more than 2, and (F) from 4 to 10percent by weight of one or more di(meth)acrylates.
 10. A compositionaccording to claim 9 wherein component (B) is a sulfonium cationicphotoinitiator.
 11. A composition according to claim 9 wherein component(C) is a 1-hydroxy phenyl ketone free radical photoinitiator.
 12. Amethod of producing a cured product, in which a composition according toclaim 1 is treated with actinic radiation.
 13. A method according toclaim 12, in which the cured product produced is a three-dimensionalshaped article and in which the article is built up from saidcomposition with the aid of a repeating, alternating sequence of steps(a) and (b); in step (a), a layer of the composition, one boundary ofwhich is the surface of the composition, is cured with the aid ofappropriate radiation within a surface region which corresponds to thedesired cross-sectional area of the three-dimensional article to beformed, at the height of this layer, and in step (b) the freshly curedlayer is covered with a new layer of the radiation-curable, liquidcomposition, this sequence of steps (a) and (b) being repeated until anarticle having the desired shape is formed and this article is, ifdesired, subjected to post-curing.